PDE 2 Phases

Quick Start

At one time, any time a phase diagram appeared with funny "tie lines" showing 2-phase regions, I started to panic.

Hopefully the app will convince you that it's all rather straightforward, especially when you see the contents of the test tube at each point in the diagram!



Surfactant Science Phase Diagram Explorer So far the aim has been to make things as general as possible. For the more complex issues of 2-phase systems the focus of attention is along the lower axis and, for consistency with the 3-Phase discussion, is restricted to WXS systems where X is often an oil. The Phase and Path options have disappeared and instead a 2-phase region is provided which you create with Width, Height and Symmetry sliders.

When you play with the sliders you will find that the phase region contains the tie-lines that confuse so many of us. What they mean is that you cannot find any formulation with the WXS values within that phase region. Instead the system splits into two. One phase has the composition at one end of the tie line, the other phase has the composition at the other end. By moving the mouse/stylus over the 2-phase region an approximate readout of the compositions of the two phases is shown in the W1,X1,S1 and W2,X2,S2 boxes as well as the ratio (from the lever rule) of the two phases. The colours shown in the test tube are coded by the position of the single phase or the two end-point phases in r,g,b colour space. Pure W is red, pure X is green and pure S is blue.

The rectangular region below the main phase region is often encountered. It typically represents the solubility limits of the lower two components in each other.

Now explore the complexities of 3-Phase systems.